Short open tags support should be optional

Short open tags are disabled by default in at least PHP 5.4
http://www.php.net/manual/en/ini.core.php#ini.short-open-tag
Short open tags are also not recommended by many, and are
explicitly discouraged by the WordPress PHP Coding standards
http://make.wordpress.org/core/handbook/coding-standards/php/#no-shorthand-php-tags

Also removed a pass-by-reference invalid call which is a strict
standard since PHP 5.4
Merge pull request #4 from soulseekah/php54-compat

Short open tags support should be optional